Well developed plate-like α-Al2O3 particles were obtained in NaCl-KCl by sintering at 1000 οC for 4 h, using Al(OH)3 powder as the starting material. The influence of silica on the phase transition and morphology development were examined. When silica was added, the main phase was γ-Al2O3 in the sample by sintering at 1000 οC, and mutinaite, SiO2 and γ-Al2O3 phases were observed in the sample by sintering at 1200 οC. Some abnormal particles were observed in the sample with Si added by sintering at 1000, 1100 and 1200 οC.